staging: wfx: firmware already handle powersave mode during scan

staging: wfx: firmware already handle powersave mode during scan

When user try to launch scan while connected, it is necessary to notify
the AP that we cannot receive data (using power save mode).

Firmware already handles this automatically so the code in the driver is
redundant and can be dropped.

By edge effect, hack of scan status in wfx_set_pm() is now useless.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20191217161318.31402-31-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>